Brita filters: What do they filter?

[yeastforbrains]

Brewer's friend water profile calculator has a function for "boil water". Boiling water is supposed to rid off temporary hardness, leaving the permanent hardness components intact. From what I understand, Brita filters also remove temporary hardness. In France we get our tap water profile provided on a government web site, and it's regularly updated. I brewed today using my tap water, run through a brita filter. To simulate the reduction of temporary hardness, I plotted my tap water profile into Brewer's friend calculator, then used the " boil water" function. Just to emphasize; I did not actually boil my mash water, I just ran it through a Brita filter! Here is a link to my Brewer's friend calculations; http://www.brewersfriend.com/mash-chemistry-and-brewing-water-calculator/?id=JMZ25YG.
As you can see, using the "boil water" function with an addition of 5 g. Calcium chloride, my mash pH should be 5.2. Attached photo of my mash pH strip. So this seems to have worked perfectly for me.

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[ajdelange]

It would be har to imagine a process which the pitcher could carry out which would remove the temporary hardness but not the permanent. You an do this by treating water with appreciable temporary harness (> 1 mEq/L) with lime but that is a bit tricky. The hardness precipitates as limestone (not the same as lime) which I would think would plug up the filter were it not removed by backwashing.

It occurs to me that I might have been to hasty in saying the Brita composition was changed b ased on # 29. It would take multiple passes to get the water down to near RO quality. This is if the ion exchange resins are both anionic and cationic.

Note: One generally cannot rely on test strips to provide accurate pH measurements in brewing.